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Pyridazine
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Nitrogen
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Nuclear
Quadrupole Coupling Constants |
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in Pyridazine |
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Nitrogen quadrupole coupling constants in pyridazine were calculated
on an re structure derived by Esselman et al. [1], an ralpha (electron diffraction) structure determined by
Almenningen et al. [2], and on a B3P86/6-31G(3d,3p) optimized structure
(this work). These calculated nqcc's are compared with the experimental
values of López et al. [3] in Tables 1 and 2. Earlier determination
of the nitrogen nqcc's had been made by Werner et al. [4]. Structure
parameters are compared in Table 3. In Table 4, ropt atomic
coordinates are given. |
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In Tables 1 - 3, subscripts a,b,c refer to the principal axes of the inertia
tensor, subscripts x,y,z to the principal axes of the nqcc tensor.
The nqcc y-axis is chosen coincident with the inertia c-axis, these
are perpendicular to the plane of the molecule. Ø (degrees)
is the angle between its subscripted parameters. ETA = (Xxx
- Xyy)/Xzz. |
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RMS is the root mean square
difference between calculated and experimental nqcc's (percentage of
average experimental nqcc). RSD is the residual stand deviation
of calibration of the B3PW91/6-311+G(df,pd) model for calculation of
the efg's/nqcc's. |
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Table 1. Nitrogen
nqcc's in Pyridazine (MHz). Calculation was made
on the re structure [1]. |
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Calc. |
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Expt. [2] |
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14N(1,2) |
Xaa |
- |
4.657 |
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4.6411(19) |
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Xbb |
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1.329 |
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1.3711(27) |
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Xcc |
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3.328 |
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3.2700(27) |
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Xab |
± |
2.646 |
± |
2.709(29) |
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RMS |
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0.042 (1.4 %) |
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RSD |
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0.030 (1.3 %) |
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Xxx |
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2.331 |
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2.412(22) |
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Xyy |
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3.328 |
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3.2700(27) |
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Xzz |
- |
5.659 |
- |
5.682(21) |
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ETA |
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0.176 |
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Øz,a |
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20.74 |
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21.01(16) |
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Øa,bi |
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30.35 |
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Øz,bi* |
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9.61 |
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* The z-axis makes an angle of 9.61o
with the external bisector ('bi') of the NNC angle and tilts toward the
adjacent nitrogen atom. |
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Table 2. Nitrogen
nqcc's in Pyridazine (MHz). Calculation was made
on the ralpha structure [1]. |
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Calc. |
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Expt. [2] |
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14N(1,2) |
Xaa |
- |
4.544 |
- |
4.6411(19) |
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Xbb |
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1.185 |
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1.3711(27) |
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Xcc |
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3.359 |
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3.2700(27) |
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Xab |
± |
2.687 |
± |
2.709(29) |
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RMS |
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0.132 (4.2 %) |
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RSD |
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0.030 (1.3 %) |
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Table 3. Nitrogen
nqcc's in Pyridazine (MHz). Calculation was made
on the B3P86/6-31G(3d,3p) ropt structure. |
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Calc. |
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Expt. [2] |
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14N(1,2) |
Xaa |
- |
4.637 |
- |
4.6411(19) |
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Xbb |
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1.276 |
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1.3711(27) |
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Xcc |
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3.361 |
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3.2700(27) |
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Xab |
± |
2.682 |
± |
2.709(29) |
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RMS |
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0.076 (2.6 %) |
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RSD |
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0.030 (1.3 %) |
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Xxx |
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2.311 |
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2.412(22) |
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Xyy |
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3.361 |
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3.2700(27) |
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Xzz |
- |
5.672 |
- |
5.682(21) |
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ETA |
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0.185 |
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Øz,a |
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21.10 |
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21.01(16) |
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Øa,bi |
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30.28 |
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Øz,bi* |
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9.18 |
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* The z-axis makes an angle of 9.18o
with the external bisector ('bi') of the NNC angle and tilts toward the
adjacent nitrogen atom. |
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| Table 3. Molecular structure parameters, re [1], B3P86/6-31G(3d,3p) ropt, and ralpha [2] (Å and degrees). |
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re |
ropt |
ralpha
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N(1)N(2) |
1.3336
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1.3251 |
1.330 |
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N(2)C(3) |
1.3302(12)
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1.3314 |
1.341 |
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C(3)C(4) |
1.3938(12)
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1.3920 |
1.393 |
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C(4)C(5) |
1.3761(16)
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1.3792 |
1.375 |
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C(3)H(3) |
1.0810(3)
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1.0861 |
1.063 |
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C(4)H(4) |
1.0802(4)
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1.0843 |
1.063 |
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N(1)N(2)C(3) |
119.29
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119.44 |
119.3 |
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N(2)C(3)C(4) |
123.86(4)
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123.76 |
123.7 |
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C(3)C(4)C(5) |
116.85(3)
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116.79 |
117.1 |
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C(4)C(3)H(3) |
121.35(6)
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121.37
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124.5
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C(5)C(4)H(4) |
122.37(4)
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122.29
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120.2
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N(2)C(3)H(3) |
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114.87 |
111.8 |
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C(3)C(4)H(4) |
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120.92 |
122.7 |
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| Table 4. Atomic coordinates,
B3P86/6-31G(3d,3p) ropt |
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a (Å) |
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b (Å) |
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N(1,2) |
- |
1.1785 |
± |
0.6625 |
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C(3,6) |
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0.0191 |
± |
1.3170 |
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C(4,5) |
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1.2234 |
± |
0.6896 |
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H(3,6) |
- |
0.1056 |
± |
2.3997 |
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H(4,5) |
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2.1401 |
± |
1.2688 |
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[1] B.J.Esselman, B.K.Amberger, J.D.Shutter, M.A.Daane, J.F.Stanton, R.C.Woods, and R.J.McMahon, J.Chem.Phys. 139,224304(2013).
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[2] A.Almenningen, G.Bjørnsen, T.Ottersen,
R.Seip, and T.G.Strand, ActaChem.Scand. A 31, 63(1977).
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[3] J.C.López, A.deLuis, S.Blanco, A.Lesarri,
and J.L.Alonso, J.Mol.Struct. 612,287(2002). |
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[4] W.Werner, H.Dreizler, and H.D.Rudolph,
Z.Naturforsch. 22a,531(1967). |
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1,2,4-Triazine |
1,2,3-Triazine |
1,3,5-Triazine |
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Table of Contents |
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Molecules/Nitrogen |
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Pyridazine.html |
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Last
Modified 14 Feb 2015 |
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